Indo-European has been described as “a branch of Indo-Uralic which was transformed under the influence of a Caucasian substratum”[Kortlandt 2002], which would imply an invasion of Indo-Uralic-speaking peoples to a territory of previous Caucasian hunter-gatherers. Such Caucasian influence has been supported recently by the finding of a genetic contribution (probably during the Mesolithic-Neolithic transition in the steppe, see below) of a pocket of Caucasus hunter-gatherers, who seem to have weathered much of the last Ice Age in apparent isolation[Jones et al. 2015].

Long-ranging language relationships are difficult to prove. If Uralic and Indo-European shared a common ancestor – Indo-Uralic[Kloekhorst 2008] –, its ancestor could be associated to the post-Swiderian east European communities with a majority of WHG ancestry and R1b1a1a-P297 lineages, similar to the Balkan hunter-gatherers from the Iron Gates. If these people and their language expanded from central and south-east European communities of the Villabruna cluster with a majority of R1b1a-L754 lineages, certain hypothetic linguistic communities can be proposed:

It would be conceivable but controversial[Prósper 2013], for example, to give credit to the nature of Proto-Basque as of Pre-Indo-European substratum[Forni 2013][Blevins 2015] – beyond pre- and post-Roman IE superstrata[Koch 2013]. This is supported by the presence of an Iberian Eneolithic sample of R1b1a-L754 (xR1b1a1a2-M269, V88-equivalent) at Els Trocs ca. 5180 BC[Haak et al. 2015], and its potential continuity in north Iberia at least until the Bell Beaker expansion[Mathieson et al. 2017].

Proto-Afroasiatic has been proposed to have emerged in the southern fringe of the Sahara in an “upside-down” view[Bender 2007], while R1b1a2-V88 lineages (and specifically its subclade R1b1a2b1b1a-V69) have been found in north and central Africa, mainly in Chadic-speaking populations, but also in west Egypt and in the Middle East[Cruciani et al. 2010]. That lineage, probably related to the Villabruna cluster, could have crossed the Mediterranean into northern Africa quite easily before the end of the Ice Age, possibly through the southern Italian Peninsula. Such an early migration into Africa is supported by the presence of R1b1a-L761 (equivalent to L754, as the sample from Villabruna) at high frequencies among the Toubou population (34%), inhabiting Chad[Haber, Mezzavilla, Bergström, et al. 2016].

The ancestry coming from outside of Africa, related to Eurasian herders[Schlebusch et al. 2017] – found in 20%-30% in the Toubou –, is potentially linked to this migration, since a good proxy for this ancestry (before the recent study of ancient Levantine ancestry) were present-day Sardinians[Pickrell et al. 2014]. From northern Africa they could have travelled south and then east, since the Sahara was an important site of occupation and crossing of hominids during the Holocene, with Fezzan-Chad-Chotts, and Chad-Chotts-Ahnet-Moyer megalake green corridors connecting northern and central Africa – with gradual desiccation of the desert, until ca. 4000 BC[Drake et al. 2011].

This old environment could have allowed the for a west-east migration, and for a sizeable population expansion in central Saharan territory. This model would agree with Chadic languages being the most divergent of the Afroasiatic group, excluding Omotic – whose population has been shown to be mainly of sub-Saharan ancestry, in contrast with other Afroasiatic peoples[Baker, Rotimi, and Shriner 2017].

A migration of this R1b1a2-V88 lineage through Iberia seems unlikely, because there is some long-term continuity of an endemic (probably Epipaleolithic) element in Morocco until about the Neolithic expansion associated with the arrival of a Levantine Natufian hunter-gatherer component, and the appearance of haplogroup E-M96[Fregel et al. 2017], whose continuity in North Africa since then is attested from east to west[Rodríguez-Varela et al. 2017]. A migration through eastern Europe seems still less likely, given the continuity of haplogroups and the ancestry components found in samples from Anatolia, the Levant, and Egypt, although it seems to be still today the preferred model of expansion of this haplogroup[Haber, Mezzavilla, Bergström, et al. 2016].

Haplogroup R2a-M124 seems to be prevalent among (ancient and modern) Dravidians, and is also found in the Caucasus, while haplogroup Q-M242 has links to Asian and Native American populations[Huang et al. 2017].

There are thus potential links of linguistic macro-groups to the expansion of certain lineages: one could thus make a simplistic association of Indo-Uralic (and Paleo-Siberian) with R1a-M420 lineages, Dravidic (and potentially Kartvelian and Altaic) with R2-M479 lineages, and Afroasiatic with R1b-M343 lineages, all departing from an older Nostratic language[Bomhard 2008], associated then with R-M207.

However, macro-languages are speculative, and their relationships highly controversial, with such ancient archaeological evolutions – and their relationship to population movements – quite difficult to ascertain. A still more speculative relation with an older Borean macro-family[Gell-Mann, Peiros, and Starostin 2009], for example, could be explained by certain expansions of P1-M45 lineages, which should in turn help determine dialectal evolutions.